The present invention relates to a multiple-layer net structure for fluid drainage, particularly for geotechnical use.
As is known, in civil engineering, geotechnical and other applications nets are used which have the purpose of ensuring the drainage of fluids through them.
Known methods use biplanar or substantially biplanar nets, i.e. nets constituted by two series of wires which intersect at a preset angle; said nets are manufactured for example by extruding plastic material with known contrarotating nozzles provided with recesses or holes capable of extruding the wires.
In said drainage systems, in order to drain liquids for example from any buried accumulation regions, it is known to arrange a layer of biplanar two-wire nets. The nets may be coupled to one or two layers, one for each face, of a filtering fabric which has the purpose of preventing clogging of the net due to the accumulation therein of solid particles of various kinds, such as soil or others.
Said nets are buried and inclined with respect to the horizontal plane, so as to allow the drainage of any liquids to be eliminated from the region in which the drainage nets are located, collecting them in another region.
A typical example of application of said nets can be the one in which the nets, coupled to filtering fabrics, are arranged on the sides and on the bottom of solid waste collection basins, urban landfills, wherein the drainage system is necessary in order to remove the liquids which form, in the course of time, due to the degradation of said solid waste and which, due to their chemical nature, might corrode the plastic membrane applied on the bottom of the landfill or might, worse still, percolate into the soil if the membrane were to break at any point.
In other applications, these nets are used to drain rainwater from regions to be kept dry, such as buried walls or others.
Although this type of net is widely used, it has been found to be susceptible to improvement, especially as regards the possibilities of obtaining efficient drainage of the liquids, which are in practice conveyed by the layers.